A conservative group that poured more than $5 million into a campaign to defend Brett M. Kavanaugh launched a new ad buy this week: thanking Sen. Susan Collins (R-Maine) for her vote supporting the nominee.

“In the midst of the chaos one leader stood out,” one of the Judicial Crisis Network’s ads says. “She did the right thing, supporting him. Thanks Susan Collins, for being a reasonable voice in Washington.”

The ad ends with a phone number for Collins’s Washington office. The group did not disclose the cost of its ad buy but said it would amount to more than $100,000 for television and digital ads.

Judicial Crisis Network is a 501(c)(4) advocacy organization — a “dark money” group that is not required to disclose the sources of its funding, regardless of the industry groups or individual donors behind them. It poured at least $5.3 million into its pro-Kavanaugh advertising campaign, much of it targeting vulnerable Senate Democrats in red and swing states. At least $1.5 million of that was spent defending Kavanaugh after Christine Blasey Ford went public with her allegation of sexual assault against him.

A liberal group of a similar stripe, Demand Justice, spent at least $700,000 of a planned $5 million campaign trying to scuttle Kavanaugh’s nomination.

Both groups represented the intense emotion and political energy generated by Kavanaugh’s nomination and confirmation fight, and both were subject to heated accusations that moneyed interests were clouding the debate.

Collins, who was the focus of a sustained effort by activists concerned by the prospect of Kavanaugh’s confirmation on the court, was one of the loudest of these voices. During a 44-minute speech on the Senate floor last week in which she announced her support for Kavanaugh, effectively sealing his confirmation, she lambasted special-interest groups that spent an “unprecedented amount of dark money” to oppose him.

On Friday, she did not immediately respond to a request sent to a spokeswoman about whether she disavowed the use of “dark money” in the campaign to support her.

Collins’s reelection chances in 2020 are already the subject of considerable intrigue. Her reputation as a moderate has taken a hit because of her support of Kavanaugh, a distinctly conservative judge who displayed a level of partisan fury at one of his hearings that raised questions about his fitness for the Supreme Court.

A group of liberal activists raised more than $3.5 million during the nomination fight to be given to Collins’s eventual opponent. Susan E. Rice, a U.S. ambassador to the United Nations and national security adviser under President Barack Obama, hinted on Twitter that she could be interested in the seat. Rice’s family is from Portland, Maine.

This week, Collins broke party ranks to vote with Democrats in a failed attempt to block a plan touted by the Trump administration for short-term health plans as an alternative to Obamacare.